Biology Reference
In-Depth Information
dramatically increasing the rate at which toads are expanding their range in
Australia (Phillips et al., 2006).
Microevolutionary changes in morphometric and scale-count variables have
occurred in Floridian populations of the alien
Anolis sagrei
(J.C. Lee, 1985, 1987),
and these changes are the side-effect of novel admixing of independently introduced
genomes from different parts of the species' native range (Kolbe et al., 2007b).
Physiological Changes
Australian snakes of the species
Pseudechis porphyriacus
are sensitive to toxin
from introduced
Bufo marinus
. Snakes from populations exposed to toads for
several decades have developed some degree of toxin resistance compared to con-
specifics from toad-naive populations. This is not an individually acquired trait, and
so must involve evolutionary adaptation of exposed populations to the toxin
(Phillips and Shine, 2006a).
Behavioral Changes
Australian snakes of the species
Pseudechis porphyriacus
from populations
exposed to toads for several decades have developed a non-learned aversion to eating
the invasive
Bufo marinus
compared to conspecifics from toad-naive populations
(Phillips and Shine, 2006a).
Native
Alytes muletensis
tadpoles, endemic to Mallorca, respond to chemical
(and perhaps visual) cues from alien
Natrix maura
snakes by decreasing their activity
levels, both in native plunge pools as well as under laboratory conditions (Griffiths
et al., 1998). Post-metamorphic individuals show the same avoidance of snake
chemical cues (Schley and Griffiths, 1998). Tadpole responses are specific to snake
cues from the introduced population of
N. maura
on Mallorca and do not extend to
conspecific snakes from the Iberian Peninsula (Griffiths et al., 1998). Use in these
tests of captive-reared
A. muletensis
naive to snakes shows that behavioral responses
are genetic and most likely acquired since the introduction of
N. maura
to the
Balearic Islands approximately 2,000 years ago. Morphological changes in tadpole
shape are also induceable by exposure to
N. maura
chemical cocktails, with
exposed tadpoles developing longer tails with deeper musculature and shallower
ventral fins (Moore et al., 2004b). This developmental plasticity again seems to
have evolved in response to the introduction of
N. maura
(Moore et al., 2004b).
Similarly, tadpoles of native
Rana aurora
derived from ponds inhabited by alien
R. catesbeiana
show increased antipredator behavior and higher survival rates when
exposed to
R. catesbeiana
in captivity than do tadpoles from evolutionarily naive
populations (Kiesecker and Blaustein, 1997). Learning could be ruled out as a
mechanism because tadpoles were derived from collected egg masses and, hence,
